Podcast
Questions and Answers
What is the typical maximum length restriction for connectors, as generally specified?
What is the typical maximum length restriction for connectors, as generally specified?
- 16 feet
- 10 feet
- 14 feet (correct)
- 8 feet
For a hand-fired, solid fuel-burning furnace using a fan for air circulation, what specific type of fan controls is required?
For a hand-fired, solid fuel-burning furnace using a fan for air circulation, what specific type of fan controls is required?
- Stoker-fired furnaces (correct)
- Other fuel burning furnaces
- Hand-fired fuel burning furnaces are no longer allowed
- Smoker-fired furnaces
What defines a central warm air heating system that circulates air solely through gravitational forces?
What defines a central warm air heating system that circulates air solely through gravitational forces?
- Forced air
- Standard
- Gravity (correct)
- Self-perpetuating air
What type of central warm air heating system relies on a fan or blower as its primary means of air circulation?
What type of central warm air heating system relies on a fan or blower as its primary means of air circulation?
What is the minimum clearance requirement in front of an unlisted, automatically fired heating system that burns gas fuel, has a temperature limit control capped at 250°F, and is installed in a large room?
What is the minimum clearance requirement in front of an unlisted, automatically fired heating system that burns gas fuel, has a temperature limit control capped at 250°F, and is installed in a large room?
According to NFPA standards, what term describes a central warm air heating system that uses gravity to circulate air?
According to NFPA standards, what term describes a central warm air heating system that uses gravity to circulate air?
When installing a forced-air system that burns gas and has a 250°F temperature limit control in a large room, what is the necessary minimum frontal clearance from combustible materials?
When installing a forced-air system that burns gas and has a 250°F temperature limit control in a large room, what is the necessary minimum frontal clearance from combustible materials?
Based on the NFPA definition, what signifies that a system is 'accessible'?
Based on the NFPA definition, what signifies that a system is 'accessible'?
According to NFPA standards, what term defines a material with the capability of undergoing combustion?
According to NFPA standards, what term defines a material with the capability of undergoing combustion?
Concerning temperature limit controls, what is the maximum permissible distance they can be located from the heat exchanger?
Concerning temperature limit controls, what is the maximum permissible distance they can be located from the heat exchanger?
Flashcards
Connector length limit
Connector length limit
Connectors in NFPA 90B are generally limited to this length for safety and standardization.
Fan controls
Fan controls
When a hand-fired, solid fuel-burning furnace has a fan, it needs these for safety.
Gravity system
Gravity system
System where air circulates via temperature differences.
Forced air system
Forced air system
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Minimum Front Clearance
Minimum Front Clearance
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Gravity system (NFPA)
Gravity system (NFPA)
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Forced air clearance
Forced air clearance
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Accessible system (NFPA)
Accessible system (NFPA)
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Combustible material
Combustible material
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Control Location Limit
Control Location Limit
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Study Notes
- NFPA 90B, 2021 Questions and Answers provided:
- Connectors are generally limited to 14 feet.
- A hand-fired, solid fuel-burning furnace equipped with a fan shall have fan controls as required for stoker-fired furnaces.
- A central warm air heating system with air circulated by gravity is a gravity system.
- A central warm air heating system equipped with a fan or blower providing the primary means for air circulation is a forced air system.
- An unlisted automatically fired system burning gas fuel with a temperature limit control no higher than 250°F, installed in a large room, requires a minimum clearance of 18 inches in front.
- A gravity system is a central warm air heating system with air circulated by gravity.
- A forced-air system burning gas fuel with a 250°F temperature limit control needs 18 inches of frontal clearance from all combustible material when installed in a large room
- "Accessible" refers to a system capable of being removed or exposed without damaging the building structure or finish and is not permanently closed in by the structure or finish of a building.
- Material capable of undergoing combustion is defined as Combustible.
- Temperature limit controls should be located no more than 2 feet downstream from the heat exchanger.
- Flammable or combustible heat transfer fluid from a solar energy system should not be used in a heat exchanger located in a duct system.
- Solar systems should be controlled so the temperature in the supply system does not exceed 250°F.
- For exposed rectangular ducts over 14 inches, the minimum galvanized sheet metal thickness is .019 inches.
- A heating system consisting of a heat exchanger with an outer casing or jacket, or an electric heating unit, connected to a supply and return system defines a central warm air heating system.
- Electric furnace systems shall have at least one register without a closeable shutter, and the duct leading thereto shall be without a damper, except where dampers and shutters cannot shut off more than 80 percent of the duct area.
- Furnace plenums shall be located a minimum of 36 inches from the heat exchanger along the centerline of airflow.
- A floor space used as a heated air supply plenum shall be restricted to one-story portions of single-family dwellings.
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